The present invention relates to a power transmission shaft, for instance, adapted to transmit a power from a gear shifter to driving wheels of a vehicle, and relates to a vehicular propeller shaft.
Conventionally, there has been proposed an elongated propeller shaft for a vehicle which transmits power from a transmission (or a change-speed gearbox) to a differential gear. The propeller shaft is constituted of two or three parts, and include a tube made of a fiber-reinforced plastic material and Cardan joints coupled to opposite end portions of the tube.
One of the joints includes a yoke that is press-fitted to one of the end portions of the tube, and a sleeve yoke that has one end attached to the side of the transmission and an opposed end connected to the yoke. The other of the joints includes a yoke that is press-fitted to the other of the end portions of the tube, and a flanged yoke that has one end attached to the side of the differential gear and an opposed end connected to the yoke.
The respective yokes include generally fork-shaped yoke bodies and cylindrical intermediate portions that has serrations on an outer circumferential surface thereof. The intermediate portions are connected with end portions of the yoke bodies which are located on a side of the tube. The yoke bodies and the intermediate portions are made of an iron-based metal and integrally formed with each other.
The tube is coupled to the yokes through the serrations by press-fitting the opposite end portions of the tube onto the outer circumferential surfaces of the intermediate portions.
Japanese Patent Application First Publication No. 2003-184853 discloses such a vehicular propeller shaft.